School #12 was a school for boys in Lodz. The students in #12a attended classes in the morning. Most students were between 8 and 13 years old, meaning that they were born between 1928 and 1933.
School #12 was located at Ulica Franciszkańska 29. The street name was changed to Franzstrasse when German occupation began in 1939. You can read more about the schools on Franciszkańska at
http://www.lodz-ghetto.com/the_schools_and_collective_prague_IV.html,26.